Apparatus for velocity measurement of a moving fluid



Oct. 21, 1952 b. FALK APPARATUS FOR VELOCITY MEASUREMENT OF A uovmcFLUID 2 Sl-iEETS-SEEET 1 Filed May 9. 1947 mm a 2 mm m a m Wi llil W1 ll l w 1w -HHHI 1H \MQ l l HM..- Wm Q a Q f. N v Q me Q. "M" "M" m NV 3.m

Oct. 21, 1952 o, K 2,614,425

APPARATUS FOR VELOCITY MEASUREMENT OF A MOVING FLUID Filed May 9. 1947 2SHEETH'IEET 2 lIvl/ENTOR. OLA/ f7". K. av

AT ORNEK Patented Oct. 21, 1952 APPARATUS FOR VELOCITY MEASUREMENT OF AMOVING FLUID Olaf Falk, Oslo, Norway, assignor to Alfred J.

Amsler & 00., Schaifhausen, Switzerland, a limited partnership ofSwitzerland Application May 9, 1947, Serial No. 747,046 In NorwayFebruary 27 1943 2 Claims.

The invention relates to an apparatus for measuring the velocity of aflowing fluid by means which are responsive to the thrust exerted by theflowing fluid and which comprise means producing a force opposed to thisthrust in order to hold the apparatus in its initial position. The forcenecessary to maintain the' equilibrium, which the moving fluid tends todisturb, is used for indicating the velocity of the fluid.

The apparatus according to the invention comprises a mechanismcounteracting the hydrodynamic thrust and compensating its effect on amovable member. This effect is used for indicating the velocity of thestream.

The accompanying drawing shows two modiflcations of an apparatusaccording to the invention.

Fig. 1 illustrates, schematically, an apparatus according to theinvention;

Fig. 2 is a view in perspective, partly in section, of a modifiedapparatus according to the invention;

Fig. 3 is an electric wiring diagram for the apparatus shown in Fig. 2;

Fig. 4 is a diagrammatic illustration of a device for electricallyindicating the measurements made by the apparatus according to Fig. 2.

With reference to Fig. 1, numeral designates a hollow cylinder in thelower part of which a shaft 2 rotates in bearings 3 and 4. A U-shapedtwo-arm lever member 5 is flxed to the lower part of shaft 2, one arm ofwhich member carries a thrust body 6, a sphere in the present case,which could also be in the form of a cylinder or a disc. A coil spring 1is fixed at its lower end to a plate 8 fixed to shaft 2, and at itsupper end to a shaft 9, coaxial with the shaft 2.

An arm I0, fixed at one end to the shaft 2, carries a member adapted tomake contact with a stationary member |2 for closing an electric circuitcomprising a source of electric current l3 and a solenoid orelectro-magnet M to which a voltmeter I5 is shunted. The core of theelectro-magnet l4 acts against the action of spring IS on one arm of acrank IS. the other universal joint with a shaft 22, the latter beingconnected by means of another universal joint with bevel gears 23 whichdrive the shaft 9 for winding and unwinding spring 1.

The shaft |9 is connected to a recording instrument, which is seen onthe right of Fig. 1. Driving shaft 3| of the recording instrumentcarries a disc 25 provided with two mobile stops or abutments 26cooperating with an arm 24 fixed on shaft l9. Marks 21 indicate theposition of abutments 26 and the extent of free rotation of the arm 24.

The recording instrument is arranged in a box 3|]. The shaft 3|,carrying the disc 25, also carries a drum 32, on the circumference ofwhich a metal wire 33 is mounted and wound according to a curve properto the instrument. A slide 35 carrying a stylus 3'! rides on a ruler 34,parallel to shaft 3|. Two pins 36 connected with slide 35 extend astridewire 33 for moving the slide along ruler 34 upon rotation of shaft 3|and drum 32. The paper. on which the stylus is recording,

is fed from a storage drum and'advanced by a drum 39 actuated by thedevice 40 which may be a clockwork.

The apparatus operates as follows:

In order to measure the velocity of the moving fluid, the lower portionof cylinder I is immersed in the stream in such position that lever 5 isat a right angle to the direction of the stream. Thereupon motor 20 andthe drive 40 of the drum 39 are started. If the contact 2 is closed,disc IB-engages roller 2|, and shaft 9 and spr ng I are rotated in thedirection of arrow 4| until the contact opens, causing drum 2| fixed onthe shaft of the motor 20 to cooperate with the friction disc l8, rotatng the shafts 9, 22 and 9 in the opposite direction until the contact l2again closes, i. e. until the tension of spring I is sumcient tocounteract the thrust acting on sphere 6. The tension of spring 1 isadjusted automatically, as, upon breaking of the circuit oftheelectro-magnet l4, spring |6' moves the rollerl1 against the disc onthe right (Fig. 1) and motor 20 acting throu h the drum 2|, the frictiondisc |8,'the shaft 22, the bevel gears 23,

. the shaft 9, winds up spring I in the direction of arrow 42.

Under the influence of the hydrodynamic pressure, the sphere 6oscillates cont nuously together .with theshaft 2, whereby the efiect offriction in bearings 3 and 4 is eliminated.

The drum 32 of the recording instrument is rotated only through an angleeoual to the difference between the one traveled by shaft l9 less theaperture angle between the two stops 26,

3 whereby the distance between the points of the zigzag curve on therecording paper 38 is reduced.

The moving fluid, water, for example, exerts a hydrodynamic thrust onthe sphere 6, which is proportional to the square of the velocity atwhich the fluid moves. The tension of the spring balancing this thrustis, consequently, proportional thereto. If the torsion angle (1 of coilspring I is plotted in a coordinate system as ordinate and the speed Vof the moving fluid as abscissa, the calibration curve will be accordingto the equation d=k1-V'*, in which k1 is a constant depending upon thesize of the body exposed to the flowing fluid and of the spring, theleverage of the body exposed to the thrust, and the properties of thefluid. In order to take into account all these factors and to obtain alinear record of the velocity, a wire 33 is so coiled about a drum 32 asto produce a variable lead. The relation of the movements A of thestylus 81 to the speed to be measured depends on the linear functionV=k2-A. The curve recorded on the paper 38 may then be integrated inorder to compute the mean value of the velocity during a certain timeperiod.

The rule 84 is provided with a scale for instantaneous readings.Fractional revolutions of drum 32 are indicated on scale 43 on disc 25moving opposite to a finger 44.

The voltmeter l5 serves to check the functioning of the instrument.

In the modification of the invention illustrated in Fig. 2, discs 5| arearranged in spaced relation at the extremity of an arm 52 in acalibrated pipe 82, which they do not obturate, the pipe beinginterposed in a fluid circuit try-passing a main stream flowing througha pipe 50, the velocity of which stream is to be measured.

Pipe 50 has two diametrically opposed threaded holes 53 in whichstuffing boxes 54 are arranged. Inside tube 55 extending through theupper stuffing box and carrying the whole measuring apparatus, aconnection member 58 is provided, in which are arranged inlet and outletpipes 51 and 58. A tube 55a extends through the lower stuffing box andis fitted from below in the connection member 56. The coaxial pipes 55and 55a serve as a guide for the whole apparatus which they sup ort andafford movement of the inlet of pipe 5! to any portion of thecross-section of pipe 60 by axiallv sliding them in the stuilin boxesand by rotation about their longitudinal axis.

The water entering pipe 51 passes throu h conduit 59. valve 80, andconduit 6| into the calibrated pipe 82 and returns throu h conduit 83, asecond valve 60. conduit 64, and the outlet pipe 58 to the main stream.The calibrated pipe 82 is traversed by another pipe 65 whichcommunicates with a pipe 86 set at a right angle to pine 65. In thelatter is fitted between end bearin s 8 and 4 a shaft 2 connected to acoiled spring I, the lo er part of which is connected to the shaft of areversible m tor 8! controlled by a reversing relay 68. The shaft 2carries at its upper end the arm 52 to which the discs 5| are connectedand another arm 69 with a blind I0 at its extremitv, wh ch. according toits position. does 'or does not intercept a luminous beam issued by asource of light producing a variable illumination of a photo-electriccell 12. The electric current passin throu h this cell controls anelectronic amplifier 13. The current passing through the latter actuatesa reversing switch 88 of the servomotor 61, as well as a conventionaltelerecording device which is not illustrated.

The electric connections are illustrated more fully in the wiringdiagram Fig. 3. The anode 14 of the photo-electric cell 12 is connectedto the positive pole of battery '15 whose negative pole is connectedthrough a resistor 18 to the oathode 16 of the cell which is alsoconnected to the grid of the amplifier 13.

If the blind Ill prevents the light emitted by the source H fromreaching the cell 12, the amplifier tube 13 is held in cut-off state bythe bias battery 19. Therefore solenoid in the anode circuit of tube 13is de-energized and releases armatures 8| and 82 of the reversing switch68 causing the direct current motor 61 to rotate the lower end of spring1 counter-clockwise.

If the blind I0 is in a position to permit light to reach thephoto-electric cell 12, a current flows from the positive pole ofbattery 15 through the photo-electric cell 12 and the resistor 18 to thenegative pole of said battery. The voltage on resistor 18 overcomes thebias voltage of battery 79 and the grid of tube 13 becomes morepositive. A current flows therefore through tube 13, energizing solenoid80 for changing the position of its armatures 8| and 82 and actuatingswitch 68 to reverse motor 81 for tensioning spring 7.

In order to set the measuring device to zero, valves 60 are closed. Uponopening of valves 80, a stream is established and shaft 2 oscillatesowing to the thrust exerted on the discs 8| and winds no spring 1. Theoscillations are also transmitted to arm 89 and blind 10, which hereplays the part of the contacts l2 of the apparatus shown in Fig. 1.Otherwise the functioning of this model is the same as that of the firstmodification.

The teletransmission of the readings taken by the device according tothe invention may be accomplished by conventional means. It will presentno difiiculty to an expert to transform these readings into a linearrelation to the measured fluid velocity. For this purpose, the shaft ofmotor 61 is connected to a shaft as designated by numeral I9 in Fig. 1and a device is used as shown on the right side of Fig. 1, the paper 38and roll 39 being replaced by a conventional rheostat serving as apotentiometer and controlling a conventional voltmeter having a linearcharacteristic. Slide 35 is in this case built for controlling therheostat. This is illustrated in Fig. 4 of the drawing. Shaft 83 ofmotor 6! drives bevel gears .84 for rotating shaft i9 provided with anarm 24. The latter abuts against one of the arms 26' which are connectedto one end of shaft 8| of drum 32' which is provided with a cam 33,actuating cam follower 35'. The latter slides on a rail 34'. Rail 34 andcam follower 85' are made of electrically conductive material. whereasthe pins 36 forming part of the cam follower and engaging cam 33' aremade of electrically insulating material. 0am follower 35 has a contactportion 31' sliding on rheostat 85 whose ends are electrically connectedwith a battery 86 when switch 81 is closed. Rail 34' and one end ofrheostat 85 are connected by conduits 88 with a voltmeter 85.

What I claim is:

.1. An apparatus for velocity measurement of a flowing fluid, comprisingin combination, a tubular casing, a first shaft, a second shaft, and acoil .spring, extending co-axially to one another in said casing inthelongitudinal direction thereof, said first shaft being connected tosaid secor ond shaft by said spring and being revolvably borne at itsends, an arm extending at a substantially right angle from said firstshaft, a thrust body located outside of said casing and within theflowing iiuid and being rigidly connected to said am and adapted toimpart a turning moment to said first shaft and to said spring, a sourceof rotary power connected with said second shaft, reversing meansconnected with said source for changing the direction of rotationthereof, actuating means controlled by said first shaft and connectedwith said'reversing means for actuating same to rotate said second shaftcounter to said turning moment to have said first shaft and said thrustbody oscillating around an equilibrium position. and means responsive tothe rotation of said second shaft until said equilibrium position isreached, thereby indicating the velocity of the flowing fluid, saidlastmentioned means including a rotatable drum operatively connected to saidsecond shaft and provided with a helicoidal guide, the pitch of whichvaries proportionally to the gauging curve of the apparatus, a scalemember parallel with the axis of said drum, a slide on said scalemember, engaged by said guide for displacement along said scale memberaway from a zero position corresponding to a zero velocity of the movingfluid by an amount proportional to the momentary velocity of the movingfluid, a sheet of paper, means for feeding the latter in a uniformmovement through a record position located below said scale member, anda writing means carried by said slide, for recording the displacementsof said slide onto that portion of said sheet of paper which ismomentarily located in said recording position.

2. An apparatus as defined in claim 1 comprising a recorder casing. afirst axle being rotatably mounted in said recorder casing and havingsaid drum fixed to it and an end portion protruding from said recordercasing, a disc fixed on said end portion and provided with two equalscale halves extending along its circumference in opposite directionsfrom a common 'zero point, two stop members mounted on said end portionand angularly adjustable along said scale halves, a second axleconnected with and rotated by said second shaft and extending coaxiallyto said first axle, and an arm fixed to said second axle and adapted toengage either one or the other of said stop members and to afiord idleoscillation of said second axle to an extent limited by said stopmembers.

OLAF' FALK.

. REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 720,188 Seidener Feb. 10. 19031,998,110 Warren Apr. 16, 1935 2,316,255 Knobel et a1. Apr. 13, 1943FOREIGN PATENTS Number Country Date 369,588 Great Britain Mar. 21, 1932

